general problems of the 2003 Chevrolet Tahoe

The tires on my vehicle wore out completely to fast even though I did what the manufacturer recommended with rotation and balance. The new replacement tires are doing the same as the original. In fact they will not stay in balance past 300 miles. I feel the suspension on the vehicle is the problem. The manufacturer was questioned and they were going to replace the original tires at about 26,000 miles but then turned around and said the car was out of warranty. I have records to indicate the care of the vehicle was taken.

This a brand new Tahoe with the regency conversion, initially it would vibrate at any speed. There's a shimmy feel to it, it was been test driven by the shop foreman it oursman Chevrolet in wheaton, MD. , he hit a pothole and this handsome SUV never recovered from the vibration. They have road force balance the tires twice, but the problem still exist. They put on a new set of tires, road force balance them. The problem (vibration) is mostly noticeable at highway speeds now. I don't feel safe and confident in the vehicle, particularly when changing lanes and it handles horribly over bumpy terrian and the such. I have file the lemon law complaint, sent a copy of my complaint to the attorney general's office in baltimore. My request for a replacement has been denied. The only avenue I have now is bbb arbitration. Help!! does anyone know what's wrong with my truck?.